Bioenergy: A Global Sustainability Effort

Bioenergy is a global commodity expected to increase in demand as the global population rises. Renewable Fuel Standard mandates require increased domestic production of biofuel from biomass. However, while industrialized nations focus on liquid biofuel development, half of the global population continues to rely primarily on solid biomass combustion to fulfill household energy needs. Technologies enabling bioenergy use are available, but scaling-up in a sustainable manner requires a thorough, multidisciplinary approach combining elements of photosynthesis, combustion, and resource economics research. Developing sustainable bioenergy requires investigating biomass production, combustion processes, and resource allocation. Rising energy demands may be met by increasing biomass production on existing agricultural lands, therefore reducing land conversion and, consequently, indirect land use change emissions. Increased biomass production is addressed by improving photosynthetic efficiency using algae as a model organism. For any form of bioenergy, using fuel efficiently and reducing emissions that are harmful to human health and the environment remain priorities. Improving combustion devices such as cookstoves helps achieve these goals in distributed bioenergy use among households in the developing world. Lastly, production and use of bioenergy will be guided by consumer preference. Through choice experiments, willingness to pay for bioenergy systems, based on system impacts on natural resources and emissions, can be estimated and used to inform public policy. The approaches above underscore the breadth of the bioenergy field and highlight the need for diverse sustainability research efforts. We hope the knowledge gained from our research can inform a variety of bioenergy applications.

Bioenergy: A Global Sustainability Effort

Bioenergy is a global commodity expected to increase in demand as the global population rises. Renewable Fuel Standard mandates require increased domestic production of biofuel from biomass. However, while industrialized nations focus on liquid biofuel development, half of the global population continues to rely primarily on solid biomass combustion to fulfill household energy needs. Technologies enabling bioenergy use are available, but scaling-up in a sustainable manner requires a thorough, multidisciplinary approach combining elements of photosynthesis, combustion, and resource economics research. Developing sustainable bioenergy requires investigating biomass production, combustion processes, and resource allocation. Rising energy demands may be met by increasing biomass production on existing agricultural lands, therefore reducing land conversion and, consequently, indirect land use change emissions. Increased biomass production is addressed by improving photosynthetic efficiency using algae as a model organism. For any form of bioenergy, using fuel efficiently and reducing emissions that are harmful to human health and the environment remain priorities. Improving combustion devices such as cookstoves helps achieve these goals in distributed bioenergy use among households in the developing world. Lastly, production and use of bioenergy will be guided by consumer preference. Through choice experiments, willingness to pay for bioenergy systems, based on system impacts on natural resources and emissions, can be estimated and used to inform public policy. The approaches above underscore the breadth of the bioenergy field and highlight the need for diverse sustainability research efforts. We hope the knowledge gained from our research can inform a variety of bioenergy applications.

Right now my work focuses on water use; specifically, consumers’ preferences for preventing agricultural water transfers and resulting “ag dry-up” that would hinder further potential for biofuel feedstocks to be grown in Colorado.

Discrete Choice Modeling is a method used to solicit consumers’ values for non-market goods or policies. It is based on random utility theory, the idea that the welfare a consumer receives is a function of the attributes/outcomes associated with a good’s consumption. To carry out a discrete choice experiment, policy options are broken down into attributes, and an experimental survey design is created where the respondent is asked which of a given combination of the attributes they would choose. These combinations are created in such a way to allow for estimation of econometric models, and the parameters estimated show how a change in the level of a given attribute impacts the welfare of the respondent. In short, it’s a way for us to determine how much consumers value policies, like preservation of water for agricultural use, and those values can be used to inform policy making.

Many improved biomass cookstove designs have been developed and been shown to reduce emissions of pollutants, such as carbon monoxide and particulate matter, compared to a basic open fire. However, more work needs to be done to: 1) design stoves that reduce emissions even further to reduce health risks to users, 2) ensure that these new stoves are more efficient and affordable so that users will be able to purchase them and experience savings resulting from reduced fuel use, and, 3) ensure that these stoves are able to maintain low levels of emissions while performing whatever cooking tasks users need them to perform based on local culture and diet.

We have decided to approach this problem by first seeking to better understand the combustion process occurring inside these stoves. Once we have gained a clear understanding of what is required to achieve low emissions and robust performance, we can work on combining these requirements with requirements related to cost and user needs.

The three subtopics seem disconnected. Can you comment on how they are related to one another? Can dried algae be used to fuel cook stoves? Will semi-gasifier cook stoves impact public assessment over traditional cook stoves? Are there some connections that I am missing?

The diversity of the individual projects reflects on the fact that bioenergy is a regionally and politically defined enterprise. Bioenergy demands in the United States are different than those in Cameroon, and even vary within the respective nations. Our individual projects showcase this diversity. We are not proposing a linear production pathway; however, the broader implications of all of our efforts are united by environmental sustainability. A better understanding of photosynthesis can lead to major improvements in biomass productivities across photosynthetic taxa, subsequently minimizing the potential environmental damages associated with indirect land use change. Design of improved biomass cookstoves is largely driven by a desire to improve conversion efficiencies to ease increasing demand on forest or other local biomass resources. Large-scale projects such as bioenergy production are unsustainable over the long term without sound public support, and economic evaluation can help bridge the gap between technological opportunities and stated public goals, such as reduced greenhouse gas emissions. Environmental sustainability is the critical link between our experiments.

Here’s a really strange question for you! Some years ago I believe that the lagoon around Venice became loaded with algae so they dredged it out by the tons and let it dry up by the beachside whereupon huge swarms of flies ate it and multiplied so much that they were a real pest (http://www.nytimes.com/1989/06/13/world/now-ven...). How practical is algae as a biofuel if it has to be dried first and curing it under the sun is problematic because of insect population growth?

This is an interesting perspective! While some macroalgae have been cultivated for centuries for food purposes, they are not generally front-runners for algal biomass production. Nevertheless, dewatering and insect predation remain significant challenges for microalgae biomass production.

Large-scale centrifugation can work for dewatering, but is energy intensive. Broad research efforts have tackled this problem. Biologically, engineered strains of cyanobacteria have been designed to secrete hydrophobic free fatty acids, which can aggregate at the surface of the media and can reduce the energy requirements for separation. Engineers have designed systems to condense cell densities before centrifugation, which reduces energy demands. These innovations could improve the practicality of algal biofuel production.

Open production of microalgae can crash if insect grazers take hold of the culture. That being said, large-scale microalgae cultures have and continue to produce nutraceuticals using these open systems. More recently, separation of the culture from the environment has proven successful in preventing these crashes, but increase operating costs of the facility. Insect populations can compromise productivities, but may be managed by environmental or production facility conditions.

People have been promoting 2nd and 3rd-generation biofuels in the developed world and improved household and distributed bioenergy technologies in the developing world for years, though progress has been slower than originally expected on both fronts. I’m curious what you think the ‘pinch points’ are for scaling up global bioenergy use in general. Do you think that sufficiently mature bioenergy technologies currently exist for either market and that policy impediments, environmental sustainability concerns, or consumer preference issues are the main hurdles to wider dissemination? Or is the demand framework generally already in place and just waiting for technologies to improve and costs to drop before the sector really takes off?

Personally, I think a combination of these factors stall dissemination, but consumer adoption may be the primary limiting factor. Yes, technologies need to improve to the point where they are cost-competitive; however, we also see cases where consumers don’t adopt new technologies even when it would be economically favorable for them to do so. In these instances, we need to borrow from psychology, behavioral economics, and the energy/water conservation literature to understand how perceptions and habit formation impact consumer choice.

Overall, I would agree with Janine’s analysis. While technological improvements would presumably favor enhanced development of bioenergy projects by reducing costs, consumer preferences will dictate implementation. For example, while GM foods have been produced for decades, food-labeling advocates recently have been challenging the product’s supermarket anonymity. This may lead to a reduction of GM crops, despite productivity losses and increased environmental impacts. Positive social perception of a given technology is critical for large-scale development.